Use amendments to make changes to an active subscription. You can use amendments to add products, update products, remove products, upgrade or downgrade products, renew subscriptions, and change a subscription's terms and conditions. You can use the Zuora user interface or the Zuora API to create amendments.
You can create amendments from three areas within Zuora Billing:
The steps for creating an amendment are similar to the steps for creating a subscription: start by filling in the amendment information, then select the amendment type and perform the applicable action (update/add/remove), and finish by activating the amendment.
Amendments can be created in arrears or in advance. For example, you can create an amendment on the day the subscription begins (for example, 1/1/2011), but date the amendment in the future (2/1/2011) so that the fees go from $0 (free trial) to $100 (monthly recurring charge) on 2/1/2011.